DEBT, NET (UNITED DOMINION REALTY, L.P.) - Summary (Details) $ in Thousands	9 Months Ended
Sep. 30, 2020 USD ($) community	Dec. 31, 2019 USD ($)
Fixed and variable rate debt
Weighted Average Interest Rate	3.01%
Long-term Debt	$ 4,917,646	$ 4,707,524
Weighted Average
Fixed and variable rate debt
Years to maturity	7 years 7 months 6 days
Fixed Rate Debt \| Mortgages Note Payable
Fixed and variable rate debt
Principal outstanding	$ 892,291	884,869
Weighted Average Interest Rate	3.36%
Communities Encumbered (in communities) \| community	13
Fixed Rate Debt \| Mortgages Note Payable \| Weighted Average
Fixed and variable rate debt
Years to maturity	7 years 1 month 6 days
Fixed Rate Debt \| Credit facilities
Fixed and variable rate debt
Principal outstanding		204,590
Variable Rate Debt \| Tax-exempt secured notes payable
Fixed and variable rate debt
Principal outstanding	$ 27,000	27,000
Weighted Average Interest Rate	0.77%
Communities Encumbered (in communities) \| community	1
Variable Rate Debt \| Tax-exempt secured notes payable \| Weighted Average
Fixed and variable rate debt
Years to maturity	11 years 6 months
United Dominion Realty L.P.
Fixed and variable rate debt
Weighted Average Interest Rate	2.52%
Communities Encumbered (in communities) \| community	2
Long-term Debt	$ 99,093	99,071
United Dominion Realty L.P. \| Weighted Average
Fixed and variable rate debt
Years to maturity	9 years 10 months 24 days
United Dominion Realty L.P. \| Mortgages Note Payable
Fixed and variable rate debt
Principal outstanding	$ 72,500
Interest rate	3.10%
United Dominion Realty L.P. \| Fixed Rate Debt
Fixed and variable rate debt
Weighted Average Interest Rate	3.10%
Communities Encumbered (in communities) \| community	1
Long-term Debt	$ 72,163	72,135
United Dominion Realty L.P. \| Fixed Rate Debt \| Weighted Average
Fixed and variable rate debt
Years to maturity	9 years 3 months 18 days
United Dominion Realty L.P. \| Fixed Rate Debt \| Mortgages Note Payable
Fixed and variable rate debt
Principal outstanding	$ 72,500	72,500
Weighted Average Interest Rate	3.10%
Communities Encumbered (in communities) \| community	1
Deferred finance costs, net	$ (337)	(365)
United Dominion Realty L.P. \| Fixed Rate Debt \| Mortgages Note Payable \| Weighted Average
Fixed and variable rate debt
Years to maturity	9 years 3 months 18 days
United Dominion Realty L.P. \| Variable Rate Debt
Fixed and variable rate debt
Weighted Average Interest Rate	0.77%
Communities Encumbered (in communities) \| community	1
Deferred finance costs, net	$ (70)	(64)
Long-term Debt	$ 26,930	26,936
United Dominion Realty L.P. \| Variable Rate Debt \| Weighted Average
Fixed and variable rate debt
Years to maturity	11 years 6 months
United Dominion Realty L.P. \| Variable Rate Debt \| Tax-exempt secured notes payable
Fixed and variable rate debt
Principal outstanding	$ 27,000	$ 27,000
Weighted Average Interest Rate	0.77%
Communities Encumbered (in communities) \| community	1
United Dominion Realty L.P. \| Variable Rate Debt \| Tax-exempt secured notes payable \| Weighted Average
Fixed and variable rate debt
Years to maturity	11 years 6 months

Number of Communities Encumbered.

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Secured debt including debt on real estate held for sale.

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- Definition

The average effective interest rate during the reporting period.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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